The present subject matter relates generally to processes for propylene recovery. More specifically, the present subject matter relates to processes for enhanced recovery of propylene and liquid petroleum gas (LPG) from the fuel gas produced in fluid catalytic cracking (FCC) units by minimizing the light ends and propylene in the unstabilized gasoline which is used as lean oil for the primary absorber of the FCC gas concentration unit.

A process for producing light olefins comprising thermal cracking. Hydrocracked streams are thermally cracked in a steam cracker to produce light olefins. A pyrolysis gas stream is separated into a light stream and a heavy stream. A light stream is separated into an aromatic naphtha stream and a non-aromatic naphtha stream. The aromatics can be saturated and thermally cracked. The integrated process may be employed to obtain olefin products of high value from a crude stream.

This method comprises: forming an expanded intermediate recirculation stream (170) from a liquid (112, 128) obtained during an upstream cooling and/or intermediate cooling step, upstream from the downstream cooling step; circulating the intermediate recirculation stream (170) at least in an upstream heat exchanger (42) to cool an upstream stream of cracked gas (102); reintroducing the reheated intermediate recirculation stream (170) in a raw cracked gas (20) upstream from at least one compressor (36, 38) of a cooling and compression stage (24). The upstream, intermediate and downstream cooling steps is carried out without a heat exchanger respectively of an upstream stream of cracked gas (102), an intermediate stream of cracked gas (114) and a downstream stream of cracked gas (140) with an external refrigeration cycle.

The present invention provides a process for recovery of propylene and LPG from the fuel gas produced in FCC unit by contacting a heavier hydrocarbon feed with FCC catalyst. The process provides an energy efficient configuration for revamping an existing unit constrained on wet gas compressor capacity or for designing a new gas concentration unit to recover propylene and LPG recovery beyond 97 mole %. The process of the present invention provides an increase propylene and LPG recovery without loading wet gas compressor with marginal increase in liquid loads.

A vacuum separator is used to separate a pitch stream from a slurry hydrocracking reactor upstream of the product fractionation column. The process and apparatus removes pitch from the product streams to enable easier separation of light VGO from heavy VGO in a fractionation column.

A plastic pyrolysis process produces light olefin product and heavier products. The light olefin products are separated in a recovery process while the heavier product can be sent to a cracking unit to be further cracked to desired products. The cracked effluent stream may be subjected to the recovery process along with the light olefin product.

Provided is a method for treating an oil gas, which can realize high-efficiency separation for and recovery of gasoline components, C.sub.2, C.sub.3, and C.sub.4 components. The method first conducts separation of light hydrocarbon components from gasoline components, and then performs subsequent treatment on a stream rich in the light hydrocarbon components, during which it is no longer necessary to use gasoline to circularly absorb liquefied gas components, which significantly reduces the amount of gasoline to be circulated and reduces energy consumption throughout the separation process. Besides, in this method, impurities, such as H.sub.2S and mercaptans, in the stream rich in the light hydrocarbon components are removed first before the separation for the components. This ensures that impurities will not be carried to a downstream light hydrocarbon recovery section, thus avoiding corrosion issues caused by hydrogen sulfide in the light hydrocarbon recovery section.

A plant for separating at least one purified hydrocarbon stream from at least one crude hydrocarbon feed stream. The plant comprises a vessel with a single foundation. The vessel comprises an absorber section and a first divided-wall column. The first divided-wall column comprises a dividing wall, a stripper section, and a stabilization section.

The power required to recover C.sub.3+ hydrocarbons from crude carbon dioxide comprising C.sub.1+ hydrocarbons and hydrogen sulfide may be reduced by distilling the crude carbon dioxide to produce carbon dioxide-enriched overhead vapor and C.sub.3+ hydrocarbon-enriched bottoms liquid such that the hydrogen sulfide is rejected with the overhead vapor. Power consumption reductions may be achieved by incorporating a heat pump cycle using carbon dioxide vapor as working fluid to provide at least a part of the refrigeration duty and using a side reboiler to reduce the bottom reboiler duty. Where the bottoms liquid is further processed to produce lighter and heavier hydrocarbon fractions, the process enables optimization of upgrading crude oil on the basis of API gravity, Reid Vapor pressure and/or viscosity.

A system for hydrogenation C.sub.3 and C.sub.4 acetylenes contained within a hydrocarbon stream generated in a stream cracker unit where a debutanizer is placed upstream of a depropanizer for more economical processing of the hydrocarbon stream to produce lighter hydrocarbons, where the system requires only one stripper tower downstream of hydrogenation to remove residual hydrogen.